A High-Speed Congenic Strategy Using First-Wave Male Germ Cells

摘要: Background In laboratory mice and rats, congenic breeding is essential for analyzing the genes of interest on specific genetic backgrounds quantitative trait loci. However, in theory it takes about 3–4 years to achieve a strain carrying 99% recipient genome at tenth backcrossing (N10). Even with marker-assisted selection, so-called ‘speed strategy’, more than year N4 or N5. Methodology/Principal Findings Here we describe new high-speed system using round spermatids retrieved from immature males (22–25 days age). We applied technique three genetically modified strains mice: transgenic (TG), knockin (KI) N-ethyl-N-nitrosourea (ENU)-induced mutants. The donor had mixed C57BL/6 (B6)∶DBA/2 B6∶129 strains. At each generation, used were selected based polymorphic marker analysis their injected into B6 oocytes. Backcrossing was repeated until N5. For TG ENU-mutant strains, N5 generation achieved 188 190 proportion B6-homozygous loci 100% (74 markers) 97.7% (172/176 markers), respectively. KI strain, day 151, all 86 markers being as early 106 N3. carrier final fertile propagated genes. Thus, established through rapid turnover between 41 44 days. Conclusions/Significance This strategy enables us produce within half year. It should provide fastest protocol precise definition phenotypic effects desired backgrounds.